The present invention relates to a hologram code reading system for reading a codified hologram reconstruction image, the process by which the hologram code reading system reads the codified hologram reconstruction image, the hologram and a card provided with the hologram.
In a conventional plastic card, individual card data such as an identification number, is recorded on the card face by such means as magnetic stripe. This manner of recording has disadvantages that include the possibility of being affected by external magnetic fields that can change or erase data, and deficiency in terms of data security in that the data can be easily altered by a generally obtainable magnetic reader/writer and used illicitly.
In order to resolve this problem, Japanese Patent Laid-open No. S62-283383 describes a card whereon personal data are recorded as a hologram reconstruction image in which a combination of image form, quantity and arrangement serves as pattern data. This hologram is arranged on the card base material according to card personal data.
However, because the construction is unclear in practical terms regarding the hologram card reading device, the type of light source to be used, the type of code reading sensor to be employed, and how the readout image is processed, the following types of problems are encountered in manufacturing.
First is difficulty in recording a hologram with a short focus distance, and since the focus distance of the played back hologram image is long, the problem of large equipment size is encountered.
Second, due to production variations and other factors affecting the code reading sensor, irregularities can occur in the distance between this code reading sensor and the hologram reconstruction image, resulting in distortion and diffractions in the hologram code reconstruction image.
Third, there is the possibility of reading error if the card material on the side where the hologram is formed is soiled.